CAPE OF GOOD HOPE. 419 



those in a proper situation never fail to witness the same series of 

 beautiful and well-defined rainbows. 



We were again affected by currents on the 5th ; and they showed 

 themselves in the formation of the short rough sea which we encoun- 

 tered. The deep-sea soundings on that day gave remarkable results ; 

 for, while the temperature of the water at the surface was 73-5°, that 

 at a depth of one hundred fathoms was 78°; although this may seem 

 somewhat singular, it may be accounted for by the circumstance that 

 we were within the influence of the tropical currents setting to the 

 southward along the eastern coast of Africa. 



On the 6th, experiments on the temperature of the water gave 

 similar results, although the difference between the surface temperature 

 and that at one hundred fathoms depth was not so great as on the pre- 

 vious day, the former being 75-5°, and the latter 78-5°. The ascertained 

 set of the ship by current this day was south half west, forty miles. At 

 noon the current was found, on trial, to flow in the same direction, but 

 with a velocity of not more than half a mile per hour. 



The ship continued to be tossed about most uncomfortably during the 

 7th, and the current set us fifty-three miles in a west-southwest direc- 

 tion. We passed close to the edge of the Aguillas Bank, where the 

 temperature of the surface water rose to 78°, and continued so until 

 5 p. m., when the water became discoloured, and it fell to 73° ; we then 

 obtained soundings with sixty fathoms of line on dead coral. During 

 this time the temperature of the air had not been higher than 70°. In 

 order to examine the temperature of the warm stream that we were 

 passing through, I shaped a course nearly at right angles to the direc- 

 tion of its flow, and while sailing sixty miles made the following obser- 

 vations : 



At noon, 



the tern 



t )eraturc 



of the 



sar£i 



co was 







78° 



" 1 P. M 





it 





u 







, 



78 



"2 



It 





u 





u 



. 







78 



"3 



u 





u 





u 



. 





, , 



77 



"4 



" 





u 





u 



. 





. 



75 



"5 



u 





u 





u 



. 







73 



"6 



" 





u 





u 



, 







69 



"7 



u 





u 





u 



. 







G8 



"8 



" 





(4 





u 



• 





• 



66 



ie time of the 



lastob 



servation 



the tempera 



ture 



of the 



air v 



On the morning of the 8th we had soundings in sixty-nine fathoms 

 water ; the direction and velocity of the current was tried by anchoring 

 a boat. The direction was found to be S. 56° W. (true), and the 

 velocity to amount to three quarters of a mile per hour. During the 

 last twenty-four hours the current had set us thirty-three miles, and in 



